C Standard Library 简明教程
C Library - <stddef.h>
stddef.h 标识符定义了多种变量类型和宏。很多这些定义也出现在其他标识符中。
The stddef.h header defines various variable types and macros. Many of these definitions also appear in other headers.
Library Variables
stddaef.h 中定义的变量类型如下：
Following are the variable types defined in the header stddef.h −
Sr.No. |
Variable & Description |
1 |
ptrdiff_t This is the signed integral type and is the result of subtracting two pointers. |
2 |
size_t This is the unsigned integral type and is the result of the sizeof keyword. |
3 |
wchar_t This is an integral type of the size of a wide character constant. |
Library Macros
stddaef.h 中定义的宏如下：
Following are the macros defined in the header stddef.h −
Sr.No. |
Macro & Description |
1 |
NULLThis macro is the value of a null pointer constant. |
2 |
offsetof(type, member-designator)This results in a constant integer of type size_t which is the offset in bytes of a structure member from the beginning of the structure. The member is given by member-designator, and the name of the structure is given in type. |